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Folic acid inhibitor Flashcards

(47 cards)

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1
Q

The 2 enzyme target for bacterial folate antagonists are

A 
Dihydropteroate synthetase (sulfonamides; competes with PABA)
Dihydrofolate reductase (trimethoprim)
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2
Q

structural analogs of PABA and competitively inhibit the enzyme dihydropteroate synthase

A

Sulfonamide drugs

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3
Q

bacteriostatic against gram (+) and gram (-) bacteria

A

Sulfonamides

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4
Q

What are the 3 groups of sulfonamides?

A

1) Oral absorbable: Sulfadiazine, Sulfisoxazole, Sulfamethoxazole ( + trimethoprim)
2) Oral nonabsorbable agents: Sulfasalazine
3) Topical agents: Sodium sulfacetamide (Sulamyd), Silver sulfadiazine (Silvadene)

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5
Q

Sulfadiazine

A

An oral absorbable sulfonamide.

Used for: UTI; nocardiosis, rheumatic fever; prophylaxis; toxoplasmosis; uncomplicated malaria

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6
Q

Sulfamethoxazole ( + trimethoprim)

A

An oral absorbable sulfonamide

Used for: URI; UTI; prophylaxis and tx of P. carinii

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7
Q

Sulfisoxazole

A

An oral absorbable sulfonamide
Used for: Otitis media; UTI; chloroquine-resistant malaria
drug resistant malaria and Toxoplasma gondii

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8
Q

Sulfasalazine

A

Oral nonabsorbable sulfonamide
Used for UC, enteritis
Delayed –release tablets used to treat RA
Anti-inflammatory properties due to cleavage of sulfasalazine to sulfapyridine and 5-aminosalicylate

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9
Q

Sodium sulfacetamide (Sulamyd)

A

Topical sulfonamide. Used in ophthalmic solution or ointment for bacterial conjunctivitis
Also used to treat chlamydia trachoma infections most common cause of preventable blindness worldwide

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10
Q

Silver sulfadiazine (Silvadene)

A

Topical sulfonamide. Topical for burn infection prophylaxis

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11
Q

Sulfonamides: distrubution

A

Distributed throughout body including CNS and fetus
Sulfamethoxazole is highly protein bound to albumin (if you have a drug that’s highly bound to albumin, may displace)
Protein binding drug interactions (narrow therapeutic index to these meds): Warfarin, phenytoin, sulfonylureas

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12
Q

Sulfonamides: Adverse Effects

A

N/V/D, HA, photosensitivity
Fever
Skin rashes- Mild to life threatening
Blood dyscrasias including hemolytic anemia
Numerous “itis’s” (nephritis, hepatitis, vasculitis)
Crystalluria

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13
Q

Competitive inhibitor of dihydrofolic acid reductase
converts dihydrofolic acid to tetrahydrofolic acid
The next step in purine synthesis
Resistance also common

A

Trimethoprim

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14
Q

Trimethoprim: adverse effects

A

1) GI

2) megaloblastic anemia, leukopenia, granulocytopenia reversed with folinic acid

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15
Q

Uses for trimethoprim

A

Can be used alone for community acquired UTI or for prophylaxis of UTI

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16
Q

Combination of Trimethoprim+sulfamethoxazole is bactericidal or -static?

A

Bactericidal.

whereas sulfamethoxazole on its own is -static

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17
Q

What is the only Only available IV sulfonamide antibiotic

A

Trimethoprim+sulfamethoxazole (Bactrim/Septra)

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18
Q

Uses for Trimethoprim+sulfamethoxazole (Bactrim/Septra)

A

Alternative agent for: Community acquired pneumonia, UTI and prostatitis, Acute otitis media (not first choice unless you have PCN allergy)
Treatment of pneumocystis carinii (HIV pts)
Bacterial diarrhea
Prophylaxis: UTI, PCP & Toxoplasma gondii in AIDS pts, Peritonitis prevention in pts with cirrhosis

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19
Q

Drug that Inhibits DNA processing by:

Inhibition of DNA topoisomerases

Study These Flashcards
A

Quinolones (fluoroquinolones)

20
Q

Drugs that Inhibit DNA processing by: Inhibition of DNA-dependent RNA polymerase

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A

Directly - rifampin

Indirectly - nitrofurantoin

21
Q

Name this drug based on action: Block bacterial DNA synthesis by inhibiting DNA topoisomerase IV and topoisomerase II (DNA gyrase)
Inhibit DNA supercoiling, transcription and repair

22
Q

Quinolones act against which bacteria?

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A

Active against gram (+) and gram (-) bacteria

Activity against Topo IV accounts for gram (+) spectrum

23
Q

Primary target of quinolones differ according to what?

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A 
according to organism.
Topo II primary, Topo IV secondary 
E.coli
Topo IV primary, Topo II secondary
Staphylococci, streptococci
24
Q

Spectrum of activity of quinolones

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A

Originally developed for enhanced gram negative coverage
Campylobacter, Enterobacter, E. coli, H. influenzae, Klebsiella, Salmonella typhi, Shigella, Vibrio cholerae
Limited activity against gram positive organisms

25
Ciprofloxacin (Cipro)
quinolone. Excellent gram negative coverage with only moderate gram positive activity
26
Levofloxacin (Levaquin) | Moxifloxacin (Avelox)
quinolones. Excellent gram negative coverage with improved gram positive coverage
27
Trovafloxacin (Trovan)
quinolone. Continued gram negative and gram positive coverage with enhanced anaerobic coverage (B. Fragilis)
28
List quinolones
Ciprofloxacin (Cipro) Levofloxacin (Levaquin) Moxifloxacin (Avelox) Trovafloxacin (Trovan)
29
Atypical pneumonia organisms that quinolones work against
Chlamydia pneumoniae | Mycoplasma pneumoniae
30
intracellular pathogens that quinolones work against
Legionella Mycobacteria tuberculosis Mycobacteria avium complex
31
clinical uses of quinolones
UTI Sinusitis Mycobacterial infections Bacterial diarrhea Salmonella, shigella, vibrio, campylobacter, traveler’s diarrhea Soft tissue, bone and joint infections Decubitis, prosthetic joints, osteomyelitis Gonococcal and chlamydial infections Pneumonia (community- or hospital-acquired) Post-exposure prophylaxis for anthrax = cipro Tx inhalation anthrax infection = levofloxacin Trovafloxacin FDA restricted to life- or limb-threatening infections Severe hepatic toxicity
32
Gatifloxacin, levofloxacin, lomefloxacin and ofloxacin eliminated by?
Renal excretion
33
Trovafloxacin and moxifloxacin are excreted?
non-renally (bile)
34
Drug interactions of quinolones
Antacids, sucralfate, iron, multivitamins CYP interactions most common with ciprofloxacin Methadone and theophylline levels increased Severe, fatal hypoglycemia with concurrent use of glyburide (diabetic pts)
35
Moxifloxacin (Avelox)
quinolone. Oral or IV; broad spectrum single daily dose; targets DNA gyrase instead of Topo IV in gram (+)
36
Gemifloxacin (Factive)
quinolone. Approved to treat mild-moderte CAP due to multi-drug resistant Streptococcus pneumoniae
37
Metronidazole (Flagyl): MOA
Bactericidal Metabolized to an intermediate that inhibits bacterial DNA synthesis and degrades existing DNA. Selectivity due to its toxic metabolite that is not produced in mammalian cells
38
Metronidazole (Flagyl): spectrum of activity
Anaerobic and protozoan infections Amebiasis; trichomoniasis; skin infections; CNS infections; intra-abdominal infections; systemic anaerobic infections; tx C. dif; bacterial vaginosis; H. pylori; acne rosacea
39
Metronidazole (Flagyl): contraindications
``` History of blood dyscrasias History of alcoholism Hepatic disease CNS disorders Visual changes 1st trimester of pregnancy- disrupts organ formation-fatal (Category B in 2nd and 3rd trimester) ```
40
Metronidazole (Flagyl): Drug interactions
Warfarin -->increased INR (international normalized ratio—how long it takes blood to clot. Increasing this= more likely to bleed) Cimetidine (p450 inhibitor)  increased metronidazole levels Lithium toxicity (bipolar conditions) ETOH disulfiram-like rxn (flushing, HA, N/V, sweating or tachycardia
41
Metronidazole (Flagyl): ADRs
``` Vertigo, HA, confusion, seizures Edema N/V/D, abdominal cramping, constipation Darkened urine, polyuria, dysuria, Transient leukopenia, neutropenia (reversible) ```
42
Nitrofurantoin (Macrodantin, Macrobid): MOA
Poorly defined; appears to require reduction for activity --> reactive forms damage DNA and interfere with RNA synthesis and DNA replication Bacteriostatic-low conc. Bactericidal-high Spectrum: Gram (+) & Gram (-)
43
Nitrofurantoin (Macrodantin, Macrobid): ADRs
GI: N/V Interstitial pulmonary fibrosis with chronic use Hemolysis in patients with G6PD deficiency Aggranulocytosis, thrombocytopenia (reversible) Peripheral neuropathies, HA, dizziness Significant skin reactions w/allergies.
44
Polymyxin B: MOA
Bactericidal Interact w/phospholipids on the outer plasma cell membranes of gram (-) bacteria, disrupting their structure. Disruption destroys bacteria’s osmotic barrier leading to lysis
45
What bacteria does Polymyxin B work against?
Gram (-) bacteria | Pseudomonas aeruginosa
46
Daptomycin (Cubicin): indications
Reserve. Used for multi-drug resistant gram (+) bacteria Bactericidal disruption of plasma membrane function by acyl tail poking hole in membrane allowing depolarization doesn’t penetrate into cytopolasm
47
Daptomycin (Cubicin): ADRs
reversible myopathy, GI (N/V/D)

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